The nominee to be the top US diplomat to Asia vowed Thursday to work for a "verifiable denuclearization" of North Korea and to help cool tempers over maritime disputes in the South China Sea.

President Barack Obama's "objective in the region is to create and ensure a stable security environment," Danny Russel told senators, adding that "economic openness" was also a main goal.

Russel, one of the main architects of the Obama administration's rebalance toward Asia, has been tapped by the president to replace Kurt Campbell at the State Department as assistant secretary of state for East Asia.

With nations such as China and India on the rise and becoming powerful economic engines, the United States has been seeking to head off any possible confrontations over markets and turf and stamp its influence on the region.

Russel told the Senate Foreign Relations Committee that he recognized "the importance of opening markets, of leveling the playing field and deepening America's economic ties to Asia."

Turning to two major concerns for regional and global security, Russel offered assurances that he would work to rein in Pyongyang's suspect nuclear program and stop South China Seas tensions flaring into conflict.

"If confirmed, I would actively pursue the verifiable denuclearization of the Korean Peninsula and work to block North Korea's efforts to proliferate or to blackmail its neighbors," Russel said.

Tensions over the North's nuclear program soared in February after it carried out a third underground atomic blast, angering the international community and triggering tightened UN sanctions supported by Pyongyang's traditional ally China.

Tempers have cooled in recent months, however, amid expectations that Pyongyang may be moving toward dialogue rather than confrontation.

China on Wednesday said North Korea has expressed willingness to rejoin long-stalled nuclear talks.

Beijing, which has faced US pressure to rein in the North, quoted the regime's veteran negotiator Kim Kye-Gwan as saying Pyongyang was willing to engage in any form of dialogue to resolve the nuclear issue peacefully.

Russel, a longtime member of the US Foreign Service who serves as senior director for Asian affairs on the White House National Security Council, added that he was deeply concerned about the plight of the North Koreans.

"North Korea is choosing not to feed its people. North Korea is prioritizing... the pursuit of a useless military capability against an imaginary threat," he added.

Another source of concern are disputes about islands in the South China Sea, through which around half of the world's cargo passes.

Tensions have soared in recent years as Vietnam and the Philippines accuse China of increasingly assertive claims to territories in sea.

Russel pledged to try to "do everything in my power to try to lower the temperature, (and) push claimants including China into a diplomatic track."

He vowed to warn Beijing that it would only flourish in "a region of law, a region of order and a region of respect for neighbors, not one in which there is space for coercion and bullying."

"The United States has a profound interest in the peaceful resolution of territorial disputes in the South and the East China seas. It's essential that we uphold freedom of navigation and commerce," Russel added.

At the end of the nomination hearing, committee chairman Senator Ben Cardin said he anticipated that Russel would be quickly confirmed to take up his new post.